How can I train marathon to achieve sub 3.15 or even sub 3 hour target within 1 year? Since I ran 800m with 2:10 (current), 5k with 18min (PB 4 years ago), 18min45sec (current), 10k with 39min (PB 4 years ago),42min (current) ? My result has declined since 4 years ago due to lack of long distance training. I am determined to train hard to achieve that goal, I am hereby to ask whether it's a realistic target and the scientific method to achieve that. I am currently running slowly 6 times per week.